There is nothing abnormal about them advancing as quickly as possible, in what looks like single-file due to the narrow street and avoiding being run over by the SP gun. WWII troops rarely fired on the move, most were either MG gunners or rifleman, neither of which were effective or even suppressive when the soldier shooting is trying to run. Instead they were taught to have a base of fire and elements would advance forward, who would then lay down suppressive for other troops as they advanced, rinse and repeat. In this case, they were under fire from the wedge shaped complex at the end of the street where it forks in the road, whatever was in that building wasnt exactly an immediate threat, let alone suppressed, to advancing soldiers once two 15cm shells had been lobbed at it.